Network terminal device, address management server, communication system, and network communication method using mac addresses to determine the ip target addresses

ABSTRACT

The present invention is intended to offer network terminal devices and an address management server which can communicate with a remote terminal without manually managing the IP address of the remote terminal. A network communication method therefor is also offered. The MAC address of a local terminal, the MAC address of the remote terminal, and the IP address of the address management server are stored in terminal devices. These terminal devices are connected with a network, and an IP address is gained. An inquiry of an IP address corresponding to the MAC address of the remote terminal is made to the address management server. When a response of the IP address of the remote terminal is made from the address management server, an access is made to this IP address.

TECHNICAL FIELD

The present invention relates to a network terminal device thatdispenses with IP address management on the terminal side and can make acommunication with a remote terminal unconsciously of IP addressesduring the communication, to an address management server capable ofgiving a notice of an IP address to this network terminal device, and toa network communication method therefor.

BACKGROUND ART

Conventionally, network phone conversation systems that make voicecommunications utilizing the Internet, Intranets, or the like have beenrun. Users of the systems have connected their respective terminals withrelay servers placed on the network. Two terminals are connected withinsuch a relay server. Thus, voice signals are encoded, sent in IPpackets, decoded, and delivered from a speaker. In this case, however,the communication quality depends on the relay server. Burden is placedon the processing of the relay server. Hence, the communication qualitydrops.

Accordingly, if two terminals are directly connected using IP addresses,stable telephone conversation not dependent on the traffic is madepossible. However, with such a network system, it is necessary to enterthe IP address of the communicating party for connection. This is quitetroublesome. To make use of it, it has been necessary that the IPaddress be previously gained and the two terminals be connected. Forthis reason, a network phone conversation system capable of connectingterminals unconsciously of IP addresses has been proposed(JP-A-2001-313671). In this network phone conversation system, amanagement server that manages user's information including the IPaddresses of terminals by means of IDs is provided. A terminal thatwishes to connect is connected with this management server. The ID ofthe remote party is entered. The IP address of the remote party isrequested. If a corresponding IP address is sent in, connection is madewith the remote terminal based on this IP address. Thus, a voicecommunication is made.

In this network phone conversation system, however, it is necessary toenter and set up the ID of the remote party as well as the ID of thelocal terminal. ID management associated with them must be performed.The difference is only that IP address management is replaced by IDmanagement. The burden on the user is still heavy.

Accordingly, a communication system for previously sending the IPaddress of the local terminal using a separate network has been proposed(JP-A-10-322391). In particular, prior to communication via a network,information including the IP address of the local terminal on thenetwork is sent to the communicating party, or remote party, using oneof plural channels such as ISDN as a separate network. The remote partysends a communication request through the communication network, usingthe IP address gained through the separate network. Thus, acommunication through the network is carried out.

If the IP address of the remote terminal is not known, a notice of theinformation including the IP address is given, using the separatenetwork. The remote party makes a communication request to this address.As a result, a communication via a network is made possible withoutperforming address management. In order to make a connection via themanagement server of the aforementioned network phone conversationsystem, the power supply of the remote terminal must be ON; otherwise,the connection cannot be made. A state in which communication isimpossible can be avoided because a communication request is made aftera connectable state is established by a separate network. Also, it isnot necessary to manage addresses. An end-to-end communication ispossible. In these respects, the burden on the user is made relativelylight.

In the background art network phone conversation system described sofar, a management server for managing the IP addresses of terminals byIDs is provided. It has been necessary to manage the ID of the remoteparty ID, as well as the ID of the local terminal. The user is urged toperform ID management for phone conversation, thus placing great burdenon him. In addition, to make a connection using a management server, thepower supply of the remote terminal must be ON; otherwise, theconnection cannot be made.

Moreover, in the communication system that previously sends an IPaddress using a separate network, the IP address is sent to the remoteparty using the separate network. The remote party sends a communicationrequest through a network using this IP address. In this way, acommunication is made. Therefore, a communication via a network is madepossible if the IP address of the remote terminal is not known. Since acommunication request is made after a connectable state is establishedby a separate network, an unconnectable state can be circumvented.Additionally, the burden on the user is relatively light in that noaddress management is necessary and that an end-to-end communication ispossible.

However, an IP address is sent using a separate network and so a networkhaving substantially plural channels such as ISDN is necessary. Usablecases are limited. In addition, although it can be said that the burdenon the user is made lighter, a procedure consisting of activating theterminal by the user himself, sending an IP address by a separatenetwork, and waiting for a communication request from the remote partymust be performed. This is difficult for users unaccustomed tocommunications such as the aged and children. Accordingly, there is ademand for a network communication terminal that permits a user to makea communication with a remote terminal via a network entirelyunconsciously of IP addresses.

DICLOSURE OF INVENTION

Accordingly, it is an object of the present invention to provide anetwork terminal device which can communicate with a remote terminalwithout managing the IP address of the remote terminal and unconsciouslyof the IP address during communication.

It is another object of the invention to provide an address managementserver which makes it unnecessary for the terminal side to manage the IPaddress of a remote terminal and which can give a notice of the IPaddress of the remote terminal during communication.

It is a further object of the invention to provide a networkcommunication method capable of communicating with a remote terminalwithout managing the IP address of the remote terminal and unconsciouslyof the IP address during communication.

To solve the foregoing problems, a network terminal device of thepresent invention is characterized as follows. When it detects that auser has made an input from an input unit for transmission, the MACaddress of the remote terminal stored in a storage portion is sent to anaddress management server. Thus, an inquiry of the IP address of theremote terminal related to the MAC address is made. When the addressmanagement server makes a response of the IP address of the remoteterminal, an access to the IP address is made.

Consequently, it is possible to communicate with the remote terminalwithout managing the IP address of the remote terminal and unconsciouslyof the IP address during communication.

An address management server of the invention is characterized in thatit has: a storage portion in which a conversion table is stored, thetable interrelating the MAC address of a terminal device and the IPaddress of the terminal device; and a control unit which, when there isa notice of the MAC address from the terminal device, adds the MACaddress to the conversion table together with a corresponding IP addressand which, when an inquiry of an IP address is made using a MAC address,gives a notice of this IP address if this IP address is in theconversion table.

In consequence, it is not necessary for the terminal side to manage theIP address of the remote terminal. During communication, it is possibleto give a notice of the IP address of the remote terminal.

The network communication method of the present invention ischaracterized as follows. The MAC address of a local terminal, the MACaddress of a remote terminal, and the IP address of an addressmanagement server are stored in a terminal device. The terminal deviceis connected with a network, and the IP address is gained. An inquiry ismade to the address management server about an IP address correspondingto the MAC address of the remote terminal. When the address managementserver makes a response of the IP address of the remote terminal, anaccess to the IP address is made.

As a result, it is possible to communicate with the remote terminalwithout managing the IP address of the remote terminal and unconsciouslyof the IP address during communication.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a structural view of the whole network of a networkcommunication system in first embodiment of the present invention.

FIG. 2(a) is a block diagram of a network terminal device in firstembodiment of the invention.

FIG. 2(b) is a diagram illustrating an address table for the networkterminal device of FIG. 2(a).

FIG. 3(a) is a block diagram of an address management server in firstembodiment of the invention.

FIG. 3(b) is a diagram illustrating a conversion table for the addressmanagement server in first embodiment of the invention.

FIG. 3(c) is a diagram illustrating a conversion table for a DNS serverin first embodiment of the invention.

FIG. 4 is a flowchart for setting up communications by IP phones by anetwork communication method of the present first embodiment.

BEST MODE FOR CARRYING OUT THE INVENTION First Embodiment

A network terminal device and an address management server in firstembodiment of the present invention and a network communication methodtherefor are hereinafter described based on the drawings. FIG. 1 is astructural view of the whole network of a network communication systemin first embodiment of the invention. FIG. 2(a) is a block diagram ofthe network terminal device in first embodiment of the invention. FIG.2(b) is a diagram illustrating an address table for the network terminaldevice of (a). FIG. 3(a) is a block diagram of an address managementserver in first embodiment of the invention. FIG. 3(b) is a diagramillustrating a conversion table for the address management server infirst embodiment of the invention. FIG. 3(c) is a diagram illustrating aconversion table for a DNS server in first embodiment of the invention.

In FIG. 1, numeral 1 is a network capable of making communications withprotocols such as TCP/IP for an Intranet, the Internet, or the like.Numeral 2 a, 2 b, 2 c, 2 d, and 2 e are network terminal devices(hereinafter referred to as the terminal devices) such as Internetphones (hereinafter referred to as IP phones) capable of making voicecommunications via the network 1. It is to be noted that the networkterminal devices 2 a, 2 b, 2 c, 2 d, and 2 e of the invention can makeimage communications, in addition to voice communications. The networkterminal devices 2 a and 2 b are sold as one set like so to speak mainand extension IP phones. During manufacture or sale, the MAC address ofa local party and the MAC address of a remote party are initially loadedinto memory and then the devices are sold. Numeral 3 is a DNS server.When the network terminal devices 2 a, 2 b, 2 c, and 2 d make inquiriesof global IP addresses (hereinafter referred to as IP addresses) withthe domain names of connection destinations instead of MAC addresses,the DNS server 3 can convert the domain names into IP addresses. Numeral4 is a DHCP server for dynamically assigning IP addresses. Numeral 5 isan address management server that intercorrelates IP addresses and MACaddresses notified from the network terminal devices 2 a, 2 b, 2 c, and2 e, registers them, and can convert MAC addresses into IP addresseswhen the network terminal devices 2 a, 2 b, 2 c, and 2 e make inquiriesof IP addresses using the MAC addresses of the connection destinations.Numeral 6 is a router. In the present mode, the terminals 2 a, 2 b, 2 c,and 2 e are connected under control of an ISP. The DNS server 3 and DHCPserver 4 manage the terminals 2 a, 2 b, 2 c, and 2 e.

Incidentally, the IP addresses of first embodiment are global IPaddresses as mentioned so far. Where used within a LAN or in othersimilar case, IP addresses can be local IP addresses. Note that thenetwork terminal device 2 e under control of the router 6 in firstembodiment does not make an inquiry to the DHCP server 4 about IPaddresses. Although not illustrated, when a connection is made with theDNS server 3 via a public network from a telephone with a gateway, thetelephone number is once converted into a given domain name fortelephone as described later. The domain name is converted into a URI(uniform resource indicator) and finally into an IP address.

FIG. 2(a) shows the block structure of the network terminal devices 2 a,2 b, 2 c, 2 d, and 2 e. Numeral 10 is a microphone for entering voice asan IP phone. Numeral 11 is a speaker for producing a decoded voicesignal as a voice as an IP phone. Numeral 12 is a voice processingcircuit that performs an A/D conversion of the voice signal from themicrophone 10 (and thus digitizes the signal), compresses the signal,produces encoded voice data, decompresses received voice data, performsa D/A conversion of it, and then produces the data as a voice signal.

Numeral 13 is an image processing portion that is provided because thenetwork terminal devices 2 a, 2 b, 2 c, 2 d, and 2 e of first embodimentalso make image communications. The image processing portiondecompresses received image data in the form of JPEG or MPEG, convertsthe data into an RGB signal, and produces an analog image signal.Numeral 14 is a display unit for displaying the image signal deliveredfrom the image processing portion 13. The received image is displayed ona display such as an LCD by the operation of the display unit 14. A CCDcamera (not shown) may be provided to accept an image signal. This iscompressed by the image processing portion 13 and sent as image data inthe form of JPEG or MPEG.

Numeral 15 is a control unit that is a central processing unit loadedwith a control program. This control unit is a means for realizing afunction of controlling the system. Numeral 16 is a storage portion thatcan store a control program and do temporal storing. Numeral 16 a is anaddress table provided in the storage portion 16. Address information towhich the network terminal devices 2 a, 2 b, 2 c, 2 d, and 2 e makeaccess is stored in the address table. Numeral 17 is a communicationportion that connects with a network and can perform a communicationmanagement and provide a communication control of a data link layer.Numeral 18 is an input unit that makes an input by depression or thelike of a ten key or a send button. The communication portion 17 managescommunications according to protocol SIP or H.323 when voicecommunications are made and according to protocol HTTP or the like whenimage communications are made. Alternatively, voice data may becompressed in the form of ADPCM or the like, image data may becompressed in the form of JPEG or the like, and transmission may be madesimply by carrying voice and image data on the data area of TCP/IP.

FIG. 2(b) shows an address table for the network terminal device 2a.Host and address information are interrelated. The MAC address of thelocal terminal is initialized to 1234567890. In the present firstembodiment, also with respect to the network terminal device 2 b thatcorresponds to the extension phone of a set of IP phones (main andextension phones) manufactured and sold as a set, the MAC address isinitialized to 1234567891 and stored in memory. The network terminaldevice 2 b is similar. The address information on the network terminaldevice 2 c is MAC address “1234567892”. The address information on thenetwork terminal device 2 e is MAC address “1234567893”. These wereafterward set by user's inputs after connection with the network 1.However, where all the network terminal devices 2 a, 2 b, 2 c, and 2 eare sold as one set, all the MAC addresses of the network terminaldevices 2 a, 2 b, 2 c, and 2 e excluding their respective localterminals (i.e., remote terminals) can be initially stored in memory.Each terminal device is provided with plural send buttons for remoteterminals, respectively. By selecting one send button, an incoming callto the selected terminal is allowed. After response by this terminal, atelephone conversation or the like is permitted. On an incoming call, abutton corresponding to the sending terminal emits light.

Address information on the network terminal device 2 d is not a MACaddress but domain name “ddd@xxx.net” that is stored in memory. This wasset afterward by an input of the user after connection with the network1. The IP address of the DNS server 3 (111.222.333.111), the IP addressof the DHCP server 4 (111.222.333.222), and the IP address of theaddress management server 5 (111.222.333.333) are stored in the addresstable 16 a. The IP address of the address management server 5 wasalready initialized on sale, in the same way as MAC addresses. Thenetwork terminal devices 2 a, 2 b, 2 c, and 2 e can make inquires to theaddress management server 5 about the IP address, using the MAC addressof the remote terminal. The terminal devices can also make an inquiry tothe DNS server 3 about the IP address, using the domain name of theremote terminal. In either case, if the IP address is gained, an IPphone communication can be made between them, using this address. Thenetwork terminal devices 2 a, 2 b, 2 c, and 2 e have DHCP clientfunctions. When connected with a network, they broad cast networksetting requests including allotment of IP addresses, whereby networksetting information including IP addresses is received from the DHCPserver 4. At this time, the IP address of the DHCP server 4 is alsoreceived and stored in the address table 16 a. Subsequently, the IPaddress stored in the address table 16 a will be used when an access ismade to the DHCP server 4. The DNS server 4 is stored in the addresstable 16 a by making an input from the input unit 18 by the user. The IPaddress of the DNS server 3 is normally notified from the ISP, orprovider, in a written document or the like, when a connection is madewith the ISP. It is also possible to receive it as network settinginformation from the DHCP server 4.

Then, the address management server and DNS server are described basedon FIG. 3,(a), (b), and (c). FIG. 3(a) shows the block structure of theaddress management server 5. Numeral 20 is a control unit that is acentral processing unit loaded with a control program. This control unitis a means for realizing a function of controlling the system. Numeral21 is a storage portion which can store a control program and dotemporal storing. Numeral 21 a is a conversion table provided in thestorage portion 21. The table interrelates the address information (MACaddresses) on the network terminal devices 2 a, 2 b, 2 c, 2 d, 2 e andIP addresses. Numeral 22 is a communication portion that connects with anetwork and can perform a communication management and provide controlof a data link layer. The block structure (not shown) of the DNS server3 is fundamentally identical with the block structure of theaforementioned address management server 5 except for the contents ofaddress information (described later) and its description is omitted.

In the conversion table 21 a of the address management server 5, IPaddress and MAC address are interrelated for each terminal as shown inFIG. 3(b). That is, the network terminal devices 2 a, 2 b, 2 c, 2 d, androuter 6 are clients of the DHCP server 4. Within the range of IPaddresses of 111.222.333.111 to 111.222.333.777, IP addresses aredynamically assigned by the DHCP server 4. The IP address111.222.333.444 of the network terminal device 2 a, the IP address111.222.333.445 of the network terminal device 2 b, the IP address111.222.333.666 of the network terminal device 2 c, the IP address111.222.333.222 of the network terminal device 2 d, and the IP address111.222.333.555:80 of the network terminal device 2 e are IP addressesdynamically assigned in this way at some instant of time.

The IP addresses are related to the MAC address 1234567890 of thenetwork terminal device 2 a, MAC address 1234567891 of the networkterminal device 2 b, and MAC address 1234567892 of the network terminaldevice 2 c, respectively. Note that the MAC address of the networkterminal device 2 d is not registered.

Then, the conversion table for the DNS server 3 interrelates IP addressand domain name for each terminal as shown in FIG. 3 (c). The networkterminal device 2 a is related to domain name “aaa@xxx.net”. The networkterminal device 2 b is related to domain name “bbb@xxx.net”. The networkterminal device 2 c is related to domain name “ccc@xxx.net”. The networkterminal device 2 d is related to domain name “ddd@xxx.net”. The networkterminal device 2 e is related to domain name “111.eee@xxx.net”.

Incidentally, ENUM (telephone number mapping) is available as a protocolfor connecting a telephone number with various applications on theInternet using a DNS. In the case of this ENUM, the telephone number isfirst converted into a domain name. This is converted into a URI by theDNS. The URI is then changed into an IP address. In a system forimplementing this ENUM function, the domain name is converted into a URIand then from the URI to an IP address by the ENUM function server.Therefore, instead of the DNS server 3, an ENUM server including thisDNS function may be positioned.

At this time, the conversion table for the ENUM server interrelates IPaddress, URI, and domain name for each terminal. Although the domainname is different from the case where a telephone number is converted,the network terminal device 2 a is related to an IP address, a URI“http://aaa.xxx.net”, and a domain name “aaa@xxx.net”, for example. Thenetwork terminal device 2 b is related to an IP address, a URI“http://bbb.xxx.net”, and a domain name “bbb@xxx.net”. The networkterminal device 2 c is related to an IP address, a URI for voicecommunication “sip:ccc@xxx.net”, and a domain name “ccc@xxx.net”. Thenetwork terminal device 2 d is related to an IP address, a URI for voicecommunication “sip:ddd@xxx.net”, and a domain name “ddd@xxx.net”. Thenetwork terminal device 2 e is related to an IP address, a URI for voicecommunication “sip:111.eee@xxx.net”, and a domain name“111.eee@xxx.net”.

When IP addresses are dynamically assigned to the network terminaldevices 2 a, 2 b, 2 c, and 2 d by the DHCP server 4, the devices updatethe IP addresses of the address management server 5 and of the DNSserver 3. The DNS server 3 can receive an IP address from the DHCPserver 4. A DDNS server (not shown) is mounted in a corresponding mannerto the DNS server 3. An IP address dynamically assigned by the DHCPserver 4 is related to a domain name, and the conversion table isupdated.

For example, when the network terminal device 2 a makes an inquiry tothe address management server 5 about the IP address of the networkterminal device 2 b using a MAC address, the address management server 5gives a notice of the IP address to the network terminal device 2 aaccording to the conversion table 21 a. In the case of the networkterminal device 2 d that is not a client of the address managementserver 5, an inquiry of the IP address is made using a domain name. TheDNS server 3 gives a notice of a corresponding IP address from theconversion table 21 a.

How a setup using MAC addresses is performed for the network terminaldevices 2 a and 2 b when connections are made is now described, theterminal devices being main and extension devices. First, the networkterminal device 2 a is connected with the network 1. Triggered by thisphysical connection, a program which is set up on connection and storedin the storage portion 16 by initialization is loaded into the centralprocessing unit, and then the control unit 15 starts the settingfunction. The control unit 15 broadcasts a network setting requestincluding allotment of IP addresses to the DHCP server 4 and thus makesa request. The control unit gains the network setting informationincluding the IP address of the local terminal (i.e., 111.222.333.444)from the DHCP server 4 and stores it in the address table 16 a.

Then, if the send button of the network terminal device 2 a isdepressed, the network terminal device 2 a reads the MAC addresses ofthe local terminal and of the network terminal device 2 b and the IPaddress of the address management server 5 from the address table 16 a.The MAC address information is set into the data area, and an IP packethaving a given header is created. At this time, the IP address of theaddress management server 5 is set into the destination IP address ofthe header. The gained IP address “1111.222.333.4441” is set into thesource IP address. A given number is set into the port number. An IPpacket created in this way is sent to the network 1.

This IP packet sent to the network 1 is received by the addressmanagement server 5. The address management server 5 takes out the MACaddress and IP address of the network terminal device 2 a and the MACaddress of the network terminal device 2 b that is the communicatingparty, from the data area. A check is made as to whether there is a MACaddress for the network terminal device 2 a. Where the MAC address ofthe network terminal device 2 a is not registered or where the addressis registered but the received IP address is different, the MAC addressand IP address of the network terminal device 2 a are interrelated andwritten into the conversion table 21 a. Then, a check is made as towhether the MAC address of the network terminal device 2 b is stored inthe conversion table 21 a.

Where the MAC address of the network terminal device 2 b is not storedin the conversion table 21 a, it is impossible to give a notice of theIP address of the network terminal device 2 b. Therefore, the addressmanagement server 5 sends a response message indicating arrival of acall to the network terminal device 2 a. Accordingly, the networkterminal device 2 a waits under this condition until the MAC address ofthe network terminal device 2 b is stored in the conversion table 21 a.Where it is impossible to give a notice of the IP address of the networkterminal device 2 b in this way, the address management server 5 sendsdisplay information that the network terminal device 2 b is notregistered with the address management server 5 to the network terminaldevice 2 a. If the display information is displayed by the networkterminal device 2 a, then the user of the network terminal device 2 acan recognize the circumstances e.g., the network terminal device 2 b isnot connected with the network.

If the network terminal device 2 b is connected with the network 1 at aninstant of time later than the time when a setup is performed for thenetwork terminal device 2 a, the control unit 15 that is triggered bythe connection reads the control program by initialization and startsthe setting function of the network terminal device 2 b. The controlunit 15 broadcasts and thus makes a network setting request includingallotment of IP addresses to the DHCP server 4. The network settinginformation including IP address “111.222.333.445” is gained from theDHCP server 4 and stored in the address table.

Subsequently, in a case when the send button of the network terminaldevice 2 b is depressed, the MAC addresses of the local terminal and ofthe network terminal device 2 a and the IP address of the addressmanagement server 5 are read from the address table. The MAC addressinformation is set into the data area, and an IP packet is created. Atthis time, the IP address of the address management server 5 is set intothe destination IP address of the header. The gained IP address“111.222.333.445” and a given port number are set into the source IPaddress. This IP packet is sent to the network 1.

When the packet is received from the network 1, the address managementserver 5 takes out the MAC address and IP address of the networkterminal device 2 b and the MAC address of the network terminal device 2a that is the communicating party. The MAC address of the networkterminal device 2 b and the IP address are interrelated and written intothe conversion table 21 a. Then, a check is made as to whether the MACaddress of the network terminal device 2 a is stored in the conversiontable 21 a.

At this time, the MAC address of the network terminal device 2 a isalready present in the conversion table 21 a and so the addressmanagement server 5 sets the IP address of the network terminal device 2a into the response message and gives a notice to the network terminaldevice 2 b. When this response message is received, the network terminaldevice 2 b sets the IP address “111.222.333.444” of the network terminaldevice 2 a into the destination IP address and sets the IP address“111.222.333.445” of the local terminal into the source IP address. Thenetwork terminal device 2 b makes an access to the network terminaldevice 2 a with protocol SIP, H.323, or the like. Consequently, thenetwork terminal device 2 b can call the network terminal device 2 a.The network terminal device 2 a responds to this call. Thus, a telephoneconversion can be made between the network terminal device 2 a and thenetwork terminal device 2 b. That is, the network terminal device 2 athat has received an IP packet for calling from the network terminaldevice 2 b takes out digital data of the calling signal from the storageportion 16 of the local terminal. A calling sound is produced from thespeaker 11 via the voice processing circuit 12. The user of the networkterminal device 2 a listening to the calling sound depresses a responsebutton (that may be in common with the send button). Thus, the voicepath with the network terminal device 2 b is connected. Consequently, avoice communication is made possible.

Under this condition, (i.e., when the MAC address and IP address of thenetwork terminal device 2 b are registered in the conversion table 21a), after communication between the network terminal devices 2 a and 2 bends, an inquiry is made to the address management server 5 about an IPaddress corresponding to the MAC address of the network terminal device2 b simply by depressing the send button of the network terminal device2 a. The IP address of the network terminal device 2 b is gained. Thus,the IP address of the network terminal device 2 b is set into thedestination IP address. The IP address of the local terminal is set intothe source IP address. It is possible to make an access to the networkterminal device 2 b with protocol SIP or H.323.

In some cases, the IP address of the local terminal device variesdynamically. Therefore, the network terminal devices 2 a and 2 b arepreferably reconnected with the network 1, or when the power supply ischanged from OFF to ON or in other similar case, a request of IP addressallotment is made to the DHCP server. Thus, whenever an IP address isgained, the MAC address and IP address of the local terminal are sent tothe address management server 5 to vary the conversion table 21 a. Inthis way, the network terminal devices 2 a and 2 b can be connected withthe network terminal device 2 a that is the communicating party making apair, simply by depressing the send button. Consequently, a peer-to-peercommunication on the network 1 can be made possible quite easily.

Furthermore, where the network terminal device is connected undercontrol of the router, if the IP address of the router dynamicallyvaries, the network terminal device cannot recognize the variation ofthe IP address. In such a case, it is desirable that the networkterminal device send the MAC address and IP address of the localterminal to the address management server 5 at regular intervals of timeto vary the conversion table 21 a.

The network terminal device 2 a can increase the number of terminalsthat can be communicated other than the network terminal device 2 b thatmakes a pair, by making an input from the input unit 18 to enter IPaddresses and domain names for terminals other than the network terminaldevice 2 b (e.g., the network terminal devices 2 d and 2 e in FIG. 2(b))or to enter a MAC address for the network terminal device 2 c in FIG.2(b), for example. The choice of the communicating party is made asfollows. The control unit 15 reads out the address table 16 a. The userselects any one of the terminal devices displayed on the display unit bythe input unit. Then, the send button is depressed. In this manner, thecommunication with the selected terminal device is made possible.

Where the address management server 5 of first embodiment is used and aconnection is made using the MAC addresses of the network terminaldevices 2 a, 2 b, 2 c, and 2 e in this way, a setup can be performedwithout any special operation simply by connecting the network terminaldevices 2 a, 2 b, 2 c, and 2 e such as main and extension phones orgroup phones with a network physically. The IP phones can be usedimmediately. Where a large number of terminal devices are installed in aLAN as a set, a switch may be mounted to select whether they are used onthe same network such that IP addresses can be gained using a RARPprotocol. Where the switch is so switched that the RARP protocol isused, it is not necessary to mount the address management server 5 aslong as on the same network. Furthermore, when a connection is made fromthe network terminal device 2 a to the other network terminal device 2c, for example, if the power supply of the network terminal device 2 cis not ON, a message storage function may be imparted to the addressmanagement server 5 so that playback can be performed.

A procedure of making a communication by the network communicationmethod of the present first embodiment is next described. FIG. 4 is aflowchart for setting up the communication using IP phones by thenetwork communication method of the present first embodiment.

First, when IP phones which are used as one set are manufactured andsold, the MAC address of one (its own) phone (hereinafter may bereferred to as the first MAC address) and the MAC address of thecommunicating party (hereinafter may be referred to as the second MACaddress) are stored in each IP phone (step 1). Under the condition wherethe MAC addresses are stored, the user purchases them (step 2). The userof the IP phones physically connects one (hereinafter may be referred toas the first IP phone) of the IP phones forming a set to a LAN (step 3).After the connection, if the user pushes the send button of the first IPphone, the DHCP server assigns an IP address to this IP phone (step 4).The IP address of the address management server is read out. The firstMAC address and the second MAC address are set into the data area, andan access is made to the address management server (step 5).

The address management server performs a check as to whether the secondIP address corresponding to the second MAC address sent in is stored ornot (step 6). Since the first IP phone of the set of IP phones was firstconnected, the second IP address is not stored. Therefore, the addressmanagement server stores the MAC address of the first IP phone and itsIP address in the conversion table (step 7), and sends a responsemessage in which the second IP address is not set to this first IP phone(step 8). Then, the server waits until the second IP phone is connected(step 9).

After the step 9, if another user connects the second IP phonephysically (step 10), and if he depresses the send button, an IP addressis assigned to this second IP phone by the DHCP server (step 11). The IPaddress of the address management server is read out. The second MACaddress and the first MAC address are set into the data area, and anaccess is made to the address management server (step 12).

The address management server performs a check as to whether the firstIP address corresponding to the first MAC address sent in is stored ornot (step 13). Since the first IP phone has been already connected andthe first IP address is stored, the address management server stores theMAC address of the second IP phone and its IP address in the conversiontable (step 14), and gives a notice of the already stored IP address ofthe first IP phone to the second IP phone (step 15).

The second IP phone that has received the already stored IP address ofthe first IP phone by this response message makes an access to the firstIP phone at this IP address and starts a peer-to-peer communication(step 16).

After the end of the communication (step 17), the previously connectedfirst IP phone makes a second access to the address management server(step 18). The address management server performs a check as to whetheran IP address corresponding to the MAC address sent in is stored or not(step 19). At this time, both IP phones are already connected, and theirIP addresses are already stored. Therefore, a notice of the alreadystored IP address of the second IP phone is given to this first IP phone(step 20). The first IP phone which was previously connected and hasreceived the IP address of this second IP phone makes an access to thesecond IP phone at this IP address and starts a peer-to-peercommunication (step 21). When this communication ends (step 22), asequence of setting procedures ends.

Since the IP addresses of the network terminal devices 2 a and 2 b mayvary dynamically, whenever the network terminal devices 2 a and 2 bsubsequently make a request for IP address allotment to the DHCP server4 and receive allotment of IP addresses, the information is preferablyregistered with the address management server 5 to update it.Furthermore, after connection with the network, registration with theaddress management server 5 and inquiry may be separately performed.That is, the send button is depressed by initialization. The MAC addressand IP address of the local terminal are registered with the addressmanagement server 5, thus completing the setup. When the send button isthen depressed, an inquiry is made to the address management server 5 asto an IP address corresponding to the MAC address of the remote terminaldevice.

In this way, according to the network communication method of thepresent first embodiment, the MAC address of itself is previously storedin one set of IP phones. In addition, the MAC address of the other isstored. A peer-to-peer communication between the IP phones of one setcan be made quite easily simply by connecting with a network without theneed for the user to perform any annoying setup at all. Even an agedperson who is not accustomed to settings of communications can easilymake a connection.

INDUSTRIAL APPLICABILITY

According to the network terminal device of the present invention, theremote terminal device can be identified using MAC addresses because MACaddresses are intrinsic to all of their respective electronic devices.Where MAC and IP addresses are interrelated in an address managementserver, the IP address of the remote terminal device can be gained bymaking an inquiry of this IP address. A peer-to-peer communication withthe remote terminal device is made possible. The terminal device doesnot need to manage the IP address of the remote terminal. When acommunication is performed, the communication can be made with theremote terminal unconsciously of the IP address.

If the MAC addresses of plural terminal devices making one set arestored in a storage portion, the remote terminal device can beidentified using MAC addresses. Where there are plural remote terminals,one send button is selected from plural send buttons. Thus, a remoteterminal can be selected. This facilitates operations for communication.Furthermore, an image processing portion for encoding and decoding imagesignal is provided. Therefore, images can be sent and received.

Furthermore, when connection is made with a network, IP addresses can beautomatically obtained. Communication can be performed without relyingon troublesome operations. If IP addresses are modified dynamically by aDHCP server, the IP address of the address management server can beupdated. An access from the remote terminal device can be made.

According to the address management server and network management methodof the present invention, the IP address of the remote terminal devicecan be found by referring to a conversion table in which MAC addressesand IP addresses are interrelated. A peer-to-peer communication with theremote terminal device can be performed. It is not necessary to managethe IP address of the remote terminal. During communication, it is easyto give a notice of the IP address of the remote terminal. It ispossible to communicate with the remote terminal unconsciously of the IPaddress. If IP addresses are dynamically modified by the DHCP server,the IP address of the address management server can be updated. Anaccess from the remote terminal device can be made.

1. A network terminal device comprising: a communication portionconnecting with a network to perform a communication; a storage portionfor storing a MAC address of a local terminal and a MAC address of aremote terminal and storing an address of an address management server;a voice processing portion for encoding and decoding a voice signal whena voice communication is performed; and an input unit operated by a userto start a communication; wherein when it is detected that an input ismade from the input unit by the user for transmission, the MAC addressof the remote terminal stored in the storage portion is sent to theaddress management server to thereby make an inquiry of an IP address ofthe remote terminal related to said MAC address and wherein when aresponse of the IP address of the remote terminal is made from theaddress management server, an access is made to this IP address.
 2. Thenetwork terminal device set forth in claim 1, wherein the remoteterminal is a plurality of network terminal devices making one set. 3.The network terminal device set forth in claim 1, wherein the networkterminal device is an IP phone.
 4. The network terminal device set forthin claim 2, wherein plural send buttons are provided for each remoteterminal, and wherein when a communication is started, one send buttonis selected from the plural send buttons and an input is made fortransmission.
 5. The network terminal device set forth in any one ofclaims 1 to 4, comprising a display unit and an image processing portionfor encoding and decoding an image signal when image communication isperformed.
 6. The network terminal device set forth in claims 1, whereinwhen said control unit detects that a user has made an input fortransmission from said input unit, the control unit sends MAC addressand IP address of the local terminal for registration with said addressmanagement server, in addition to the MAC address of the remoteterminal.
 7. The network terminal device set forth in claim 6, whereinwhen connection is made with said network, said control unit broadcastsa request for allotment of an IP address, receives allotment of an IPaddress from a DHCP server, and informs said address management serverthat the IP address of the local terminal has been updated by the DHCPserver.
 8. An address management server comprising: a communicationportion connecting with a network to perform a communication; a storageportion stored with a conversion table in which MAC addresses ofterminal devices and IP addresses of the terminal devices areinterrelated; and a control unit which, when a notice of a MAC addressis given from a terminal device, adds the MAC address to the conversiontable together with a corresponding IP address and which, when aninquiry of an IP address is made using a MAC address, gives a notice ofthe IP address, if the IP address is present in the conversion table. 9.The address management server set forth in claim 8, wherein when anotice that an IP address has been updated by a DHCP server is givenfrom a terminal device, the IP address in the conversion table isupdated.
 10. A network communication method comprising the steps of:storing a MAC address of a local terminal, a MAC address of a remoteterminal, and an IP address of an address management server in aterminal device; connecting the terminal device with a network andgaining an IP address; making an inquiry to the address managementserver as to an IP address corresponding to the MAC address of theremote terminal; and making an access to the IP address of the remoteterminal when the address management server makes a response of this IPaddress.
 11. A communication system comprising: a plurality of networkterminal devices each having a communication portion connecting with anetwork to perform a communication, a storage portion for storing a MACaddress of a local terminal and a MAC address of a remote terminal andstoring an address of an address management server, and an input unitoperated by a user to start a communication; and the address managementserver having a communication portion connecting with a network toperform a communication, a storage portion stored with a conversioncable in which the MAC addresses of the network terminal devices and IPaddresses of the network terminal devices are interrelated, and acontrol unit which, when a notice of a MAC address is given from anetwork terminal device, adds the MAC address to the conversion tabletogether with a corresponding IP address and which, when an inquiry ofan IP address is made using a MAC address, gives a notice of the IPaddress, if it is present in the conversion table; wherein a notice ofthe IP address of the remote terminal is given to the plurality ofnetwork terminal devices from the address management server and then thenetwork terminal devices make an access to this IP address and performdirect communication between the network terminal devices.
 12. Thecommunication system set forth in claim 11, further including a DNSserver having a communication portion connected with a network toperform a communication, a storage portion stored with a conversiontable in which domain names of the network terminal devices and IPaddresses of the network terminal devices are interrelated, and acontrol unit which, when an inquiry of an IP address is made using adomain name from a network terminal device, gives a notice of this IPaddress if it is present in the conversion table, and wherein a noticeof the IP address of the remote terminal is given to the plurality ofnetwork terminal devices from the DNS server and then the networkterminal devices make an access to this IP address and perform directcommunication between the network terminal devices.
 13. Thecommunication system set forth in claim 12, wherein said DNS server isan ENUM server.
 14. The communication system set forth in claim 12,further including a DHCP server for dynamically assigning the IPaddresses of said plurality of network terminal devices, and whereinwhen the IP addresses are dynamically assigned by the DHCP server, thenetwork terminal devices update an IP address of the address managementserver or of the DNS server.
 15. The network terminal device set forthin claim 2, wherein when said control unit detects that a user has madean input for transmission from said input unit, the control unit sendsMAC address and IP address of the local terminal for registration withsaid address management server, in addition to the MAC address of theremote terminal.
 16. The network terminal device set forth in claim 3,wherein when said control unit detects that a user has made an input fortransmission from said input unit, the control unit sends MAC addressand IP address of the local terminal for registration with said addressmanagement server, in addition to the MAC address of the remoteterminal.
 17. The network terminal device set forth in claim 4, whereinwhen said control unit detects that a user has made an input fortransmission from said input unit, the control unit sends MAC addressand IP address of the local terminal for registration with said addressmanagement server, in addition to the MAC address of the remoteterminal.
 18. The network terminal device set forth in claim 5, whereinwhen said control unit detects that a user has made an input fortransmission from said input unit, the control unit sends MAC addressand IP address of the local terminal for registration with said addressmanagement server, in addition to the MAC address of the remoteterminal.